Input–Output Logic of ODES WY-35A4 Three-Phase Voltage Supervision Relay

TonyZhang
Sep 27, 2025
2 min read

In engineering practice, different systems may require different alarm and reset logics for three-phase undervoltage supervision relays. To align design, commissioning, and operations, ODES offers two typical logic strategies within the WY-35A4 series:

Standard Logic (WY-35A4)
Customized Logic (WY-35A4-T)

Understanding their differences helps engineers select the right model and validate performance in the field.

Standard Logic: WY-35A4

Pickup logic: If any one phase voltage drops below the set threshold, the relay starts timing (default 0 ms, adjustable). When the delay expires, the relay contact changes state and outputs a signal.
Reset logic: Contacts return to the initial state once all three phases exceed the reset value (typically 1.1 × pickup setting).

Typical applications:

PT voltage supervision.
Metering voltage supervision.

Customized Logic: WY-35A4-T

Pickup logic: Timing starts only when all three phases drop below the threshold (default 0 ms, adjustable). When the delay expires, the relay contact changes state and outputs a signal.
Reset logic: Contacts return to the initial state when any one phase exceeds the reset value (typically 1.1 × pickup setting).

Typical applications:

Grounding switch blocking circuits, ensuring circuits are fully de-energized before closing grounding switches for maintenance.
Rail transit and other systems requiring strict blocking logic.

Engineering Value

By offering both standard undervoltage logic and customized blocking logic, ODES WY-35A4 relays give engineers flexibility to design according to project needs—whether for conventional PT supervision or safety-critical interlocking circuits.

Choosing the right undervoltage relay logic can make the difference between a nuisance alarm and a safe interlock. If your project requires guidance on PT supervision or blocking logic design, our engineers are ready to support.

📩 tonyzhang@odes.com.cn

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🌐 https://www.odes-electric.com/